Lagoon sea slug (Tenellia adspersa)
Tenellia adspersa crawling on Ruppia with the mollusc Rissoa membranacea.
Photographer: Dennis R. Seaward Copyright: Dennis R. Seaward
Tenellia adspersa
Photographer: Dennis R. Seaward Copyright: Dennis R. Seaward
Two animals crawling on Zostera and Obelia.
Photographer: Dennis R. Seaward Copyright: Dennis R. Seaward
Distribution data supplied by the Ocean Biodiversity Information System (OBIS). To interrogate UK data visit the NBN Atlas.Map Help
| Researched by | Nicola White | Refereed by | Dr Richard S.K. Barnes |
| Authority | (Nordmann, 1845) | ||
| Other common names | - | Synonyms | Tenellia pallida (Nordmann, 1845), Embletonia pallida (Nordmann, 1845) |
Summary
Description
Recorded distribution in Britain and Ireland
The few British records are from the Firth of Forth, Scotland, near St Osyth, Essex, the Fleet, Dorset, the Bristol Channel, off Pembrokeshire and Liverpool Bay.Global distribution
Recorded from the eastern and western North Atlantic, Baltic, Mediterranean Sea, Black Sea, Azov Sea, Caspian Sea, Japan, Pacific coast of USA, BrazilHabitat
Found intertidally and in the shallow sublittoral. A euryhaline species often in harbours, estuaries and canals.Depth range
-Identifying features
- Few cerata arranged in groups of two or three along each side of the body.
- Body pale brown and marked with tiny black spots as are the cerata.
- Digestive gland is pale orange in colour.
- Oral tentacles are small and directed laterally.
Additional information
No text enteredListed by
Biology review
Taxonomy
| Phylum | Mollusca | Snails, slugs, mussels, cockles, clams & squid |
| Class | Gastropoda | Snails, slugs & sea butterflies |
| Order | Nudibranchia | Naked gilled, shell-less sea slugs |
| Family | Trinchesiidae | |
| Genus | Tenellia | |
| Authority | (Nordmann, 1845) | |
| Recent Synonyms | Tenellia pallida (Nordmann, 1845)Embletonia pallida (Nordmann, 1845) | |
Biology
| Typical abundance | Moderate density | ||
| Male size range | Up to 8mm | ||
| Male size at maturity | 3.60mm | ||
| Female size range | 3.60mm | ||
| Female size at maturity | |||
| Growth form | Lanceolate | ||
| Growth rate | Data deficient | ||
| Body flexibility | |||
| Mobility | |||
| Characteristic feeding method | No information, Predator | ||
| Diet/food source | No information | ||
| Typically feeds on | Hydroids, especially %Cordylophora caspia%, Laomeda spp. and %Protohydra leuckarti% | ||
| Sociability | |||
| Environmental position | Epifaunal | ||
| Dependency | - | ||
| Supports | - | ||
| Is the species harmful? | Data deficient | ||
Biology information
Tenellia adspersa can rapidly devour hydroid colonies, exhausting its own food supply. It has been suggested that the developmental plasticity and rapid growth of this species enables it to disperse to new locations to find new food.Habitat preferences
| Physiographic preferences | Estuary, Isolated saline water (Lagoon), Enclosed coast / Embayment |
| Biological zone preferences | Lower eulittoral, Sublittoral fringe, Upper infralittoral |
| Substratum / habitat preferences | Macroalgae, Cobbles, Pebbles, Small boulders |
| Tidal strength preferences | Moderately Strong 1 to 3 knots (0.5-1.5 m/sec.), Strong 3 to 6 knots (1.5-3 m/sec.), Weak < 1 knot (<0.5 m/sec.) |
| Wave exposure preferences | Sheltered, Very sheltered |
| Salinity preferences | Low (<18 psu), Variable (18-40 psu) |
| Depth range | |
| Other preferences | No text entered |
| Migration Pattern | Non-migratory / resident |
Habitat Information
Recorded at depths from 1 to 34 m. The species has been observed to survive and breed in salinities from 50 psu to 5.3 psu. The ranges and ecological features of the nudibranch are very similar to the hydroid Cordylophora caspia and they co-exist everywhere, which suggests some connection. The wide geographic distribution of Tenellia adspersa is probably due to passive transportation of adults and egg masses by Cordylophora colonies on ships.Life history
Adult characteristics
| Reproductive type | Gonochoristic (dioecious) | |
| Reproductive frequency | Annual protracted | |
| Fecundity (number of eggs) | 11-100 | |
| Generation time | <1 year | |
| Age at maturity | 19 to 20 days | |
| Season | Insufficient information | |
| Life span | <1 year |
Larval characteristics
| Larval/propagule type | - |
| Larval/juvenile development | Direct development |
| Duration of larval stage | No information |
| Larval dispersal potential | 100 -1000 m |
| Larval settlement period | Insufficient information |
Life history information
Tenellia adspersa has a subannual lifecycle with a short generation time of as little as 20 days when reared at 20 degrees C and 30 ppt on the hydroid Cordylophora lacustris. The animals may spawn 3 to 5 times a day with 25 to 50 eggs per spawn (Chester, 1996). The spawn consists of a short, curved, lozenge-shaped mass. The period from spawning to hatching lasts 4-5 days. The method of development varies with the environmental conditions. Metamorphosis normally takes place within the egg capsule, hatching as a juvenile. In animals that have been starved a switch to pelagic non-feeding or planktotrophic development has been observed.Sensitivity review
The MarLIN sensitivity assessment approach used below has been superseded by the MarESA (Marine Evidence-based Sensitivity Assessment) approach (see menu). The MarLIN approach was used for assessments from 1999-2010. The MarESA approach reflects the recent conservation imperatives and terminology and is used for sensitivity assessments from 2014 onwards.
Physical pressures
| Intolerance | Recoverability | Sensitivity | Evidence/Confidence | |
| High | Very low / none | Very High | Low | |
| The species lives on hydroids attached to rocks, algae or artificial substrates. The loss of the substrate would cause removal of the species and recovery would be very low due to the limited distribution of the host species. | ||||
| High | Very low / none | Very High | Low | |
| The hydroids on which Tenellia adspersa lives may be killed by smothering, so removing the species food source. Recovery would be low due to the limited distribution of the Tenellia adspersa. | ||||
| Low | High | Low | Low | |
| The species is probably able to tolerate siltation as it occurs in estuaries and lagoons where siltation naturally occurs. Recovery from any damage could be rapid due to the fast growth and reproductive rates of the species. | ||||
| No information | ||||
| High | Very low / none | Very High | Low | |
| The low shore position and soft-bodied nature of this species suggests that it is unlikely to tolerate desiccation. Where the species is exposed to desiccation, individuals are likely to be present deeper at the site, so providing a source for recolonization. Where unaffected individuals are not present recovery would be low due to the species limited distribution. | ||||
| High | Very High | Low | ||
| The low shore position and soft-bodied nature of this species suggests that it is unlikely to tolerate emersion as it would suffer desiccation. Where the species is exposed to emersion, individuals are likely to be present deeper at the site, so providing a source for recolonization. Where unaffected individuals are not present recovery would be low due to the species limited distribution. | ||||
| No information | ||||
| Tolerant | Not relevant | Not sensitive | Moderate | |
| The species is normally found at sites of slow water current, but it has been observed to withstand rapid water flow (0.8-2.4m/sec.) as evidenced by animals occupying the lattices of pipe lines. | ||||
| No information | ||||
| Low | Moderate | Low | Low | |
| Tenellia adspersa can live under a wide range of water temperatures since it occurs in lagoons which undergo great seasonal temperature variation and it occupies a wide geographic range, from the Lofoten Islands to the Mediterranean. | ||||
| No information | ||||
| Tolerant | Not relevant | Not sensitive | Low | |
| Neither the species or the hydroids on which it lives are dependant on light availability, so it would not be affected by a change in turbidity. | ||||
| No information | ||||
| High | Low | High | Very low | |
| The species is largely known from wave sheltered locations, which suggests an inability to tolerate exposed conditions. Recovery would be low due to the limited distribution of the species. | ||||
| No information | ||||
| Tolerant | Not relevant | Not sensitive | Not relevant | |
| The species probably has very limited capacity for noise perception | ||||
| Tolerant | Not relevant | Not sensitive | Not relevant | |
| The species probably has very limited capacity for visual perception. | ||||
| High | Moderate | Moderate | Low | |
| The species occurs in the surface hydroid turf and it is soft-bodied so would be easily damaged upon impact. In addition, a passing dredge is likely to damage its substratum (see substratum loss above). Therefore, an intolerance of high has been recorded. | ||||
| Low | High | Low | Moderate | |
| Tenellia adspersa would not be affected by displacement, indeed the species has formed colonies in distant locations by transport on ships. | ||||
Chemical pressures
| Intolerance | Recoverability | Sensitivity | Evidence/Confidence | |
| No information | Not relevant | No information | Not relevant | |
| Insufficient information | ||||
| No information | Not relevant | No information | Not relevant | |
| Insufficient information | ||||
| No information | Not relevant | No information | Not relevant | |
| Insufficient information | ||||
| No information | Not relevant | No information | Not relevant | |
| Insufficient information | ||||
| No information | Not relevant | No information | Not relevant | |
| Insufficient information | ||||
| Low | High | Low | High | |
| The species can tolerate a wide range of salinities and will reproduce in salinities of 3 psu to 40 psu (Roginskaya, 1970). | ||||
| No information | ||||
| No information | Not relevant | No information | Not relevant | |
| Insufficient information | ||||
Biological pressures
| Intolerance | Recoverability | Sensitivity | Evidence/Confidence | |
| No information | Not relevant | No information | Not relevant | |
| Insufficient information | ||||
| No information | None | No information | Not relevant | |
| Insufficient information | ||||
| No information | Not relevant | No information | Not relevant | |
| Insufficient information | ||||
| No information | Not relevant | No information | Not relevant | |
| Insufficient information | ||||
Additional information
Importance review
Policy/legislation
| Wildlife & Countryside Act | Schedule 5, section 9 |
| UK Biodiversity Action Plan Priority | |
| Species of principal importance (England) | |
| Species of principal importance (Wales) | |
| Features of Conservation Importance (England & Wales) |
Status
| National (GB) importance | Nationally rare | Global red list (IUCN) category | - |
Non-native
| Native | - | ||
| Origin | - | Date Arrived | - |
Importance information
-none-Bibliography
Anonymous, 1999s. Saline lagoons. Habitat Action Plan. In UK Biodiversity Group. Tranche 2 Action Plans. English Nature for the UK Biodiversity Group, Peterborough., English Nature for the UK Biodiversity Group, Peterborough.
Antsulevich, A.Ye. & Starobogatov, Ya.I., 1991. First Record of a Nudibranch Mollusk (Tritoniformes) in the Caspian Sea. Hydrobiological Journal, 27, 71-74.
Chester, C.M., 1996. The effect of adult nutrition on the reproduction and development of Tenellia adspersa (Nordmann, 1845). Journal of Experimental Marine Biology and Ecology, 198, 113-130.
Hayward, P.J. & Ryland, J.S. (ed.) 1995b. Handbook of the marine fauna of North-West Europe. Oxford: Oxford University Press.
Howson, C.M. & Picton, B.E., 1997. The species directory of the marine fauna and flora of the British Isles and surrounding seas. Belfast: Ulster Museum. [Ulster Museum publication, no. 276.]
Picton, B. E. & Morrow, C.C., 1994. A Field Guide to the Nudibranchs of the British Isles. London: Immel Publishing Ltd.
Roginskaya, I.S., 1970. Tenellia adspersa, a nudibranch new to the Azov Sea with notes on its taxonomy and ecology. Malacological Review, 3, 167-174.
Datasets
Bristol Regional Environmental Records Centre, 2017. BRERC species records recorded over 15 years ago. Occurrence dataset: https://doi.org/10.15468/h1ln5p accessed via GBIF.org on 2018-09-25.
Conchological Society of Great Britain & Ireland, 2018. Mollusc (marine) records for Great Britain and Ireland. Occurrence dataset: https://doi.org/10.15468/aurwcz accessed via GBIF.org on 2018-09-25.
NBN (National Biodiversity Network) Atlas. Available from: https://www.nbnatlas.org.
Norfolk Biodiversity Information Service, 2017. NBIS Records to December 2016. Occurrence dataset: https://doi.org/10.15468/jca5lo accessed via GBIF.org on 2018-10-01.
OBIS (Ocean Biodiversity Information System), 2023. Global map of species distribution using gridded data. Available from: Ocean Biogeographic Information System. www.iobis.org. Accessed: 2023-06-04
Citation
This review can be cited as:
Last Updated: 19/08/2008
